Related Person Transactions	9 Months Ended
Related Person Transactions	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Person Transactions	Related Person Transactions We have relationships and historical and continuing transactions with Five Star, RMR LLC, RMR Inc., Affiliates Insurance Company, or AIC, and others related to them, including other companies to which RMR LLC provides management services and which have trustees, directors and officers who are also our Trustees or officers. Five Star. We are currently one of Five Star’s largest stockholders. As of September 30, 2019, we owned 423,500 of Five Star’s common shares, after giving effect to the one-for-ten reverse stock split of Five Star common shares that Five Star effected on September 30, 2019, or approximately 8.3% of Five Star’s outstanding common shares. Five Star is our largest tenant and the manager of our managed senior living communities. RMR LLC provides management services to both us and Five Star. As of September 30, 2019, ABP Acquisition LLC, a subsidiary of ABP Trust, the controlling shareholder of RMR Inc., owned 35.4% of Five Star's outstanding common shares. Adam D. Portnoy, the Chair of our Board of Trustees and one of our Managing Trustees, is the sole trustee, an officer and the controlling shareholder of ABP Trust and a managing director of Five Star. Our other Managing Trustee also serves as secretary of Five Star. Five Star’s president and chief executive officer and chief financial officer and treasurer are officers and employees of RMR LLC. On April 1, 2019, we entered into the Transaction Agreement, pursuant to which we agreed to modify our existing business arrangements with Five Star, subject to certain conditions and the receipt of various approvals. See Note 10 for further information regarding our relationships, agreements and transactions with Five Star and Note 6 for further information regarding our investment in Five Star. Our Manager, RMR LLC. We have two agreements with RMR LLC to provide management services to us. See Note 11 for further information regarding our management agreements with RMR LLC. See Note 8 for information relating to the annual share awards we made in September 2019 to our officers and certain other employees of RMR LLC and common shares we purchased from our officers and certain other employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares to them. We include amounts recognized as expense for share awards to RMR LLC employees in general and administrative expenses in our condensed consolidated statements of comprehensive income (loss). RMR Inc. RMR LLC is a majority owned subsidiary of RMR Inc. and RMR Inc. is the managing member of RMR LLC. Adam D. Portnoy, the Chair of our Board of Trustees and one of our Managing Trustees, is the sole trustee, an officer and the controlling shareholder of ABP Trust, which is the controlling shareholder of RMR Inc., a managing director, president and chief executive officer of RMR Inc., and an officer and employee of RMR LLC. Jennifer B. Clark, our other Managing Trustee and our Secretary, also serves as a managing director and as executive vice president, general counsel and secretary of RMR Inc., an officer of ABP Trust, an officer and employee of RMR LLC. Other officers and employees of RMR LLC also serve as our officers. On July 1, 2019, we sold all of the 2,637,408 shares of class A common stock of RMR Inc. that we owned in an underwritten public offering at a price to the public of $40.00 per share pursuant to the underwriting agreement among us, RMR Inc., certain other REITs managed by RMR LLC that also sold their class A common stock of RMR Inc. in the offering, and the underwriters named therein. We received net proceeds of $98,557 from this sale, after deducting the underwriting discounts and commissions and other offering expenses. AIC. We, ABP Trust, Five Star and four other companies to which RMR LLC provides management services currently own AIC in equal amounts. We and the other AIC shareholders historically participated in a combined property insurance program arranged and reinsured in part by AIC. The policies under that program expired on June 30, 2019, and we and the other AIC shareholders elected not to renew the AIC property insurance program; we have instead purchased standalone property insurance coverage with unrelated third party insurance providers. As of September 30, 2019 and December 31, 2018, our investment in AIC had a carrying value of $9,340 and $8,632, respectively. These amounts are included in other assets, net in our condensed consolidated balance sheets. We recognized income related to our investment in AIC, which is presented as equity in earnings of an investee in our condensed consolidated statements of comprehensive income (loss). Our other comprehensive income (loss) includes our proportionate part of unrealized gains (losses) on fixed income securities that are owned by AIC related to our investment in AIC. AIC is in the process of dissolving. In connection with its dissolution, we expect to receive a capital distribution in the fourth quarter of 2019. For further information about these and other such relationships and certain other related person transactions, refer to our Annual Report.